Fast wideband integral solution for hybrid finite element / boundary integral problems with higher order boundary functions

A fast integral solver for finite element / boundary integral (FE/BI) problems is presented. In general, the BI part is formulated by Rao-Wilton-Glisson (RWG) basis functions. For reduction of the necessary unknowns while maintaining a certain solution accuracy, the RWG functions can be supplemented by hierarchical Nedelec kind basis functions. By a low-frequency stable fast solver combining the multilevel Green´s function interpolation method with fast Fourier transform acceleration (MLIPFFT) and the multilevel fast multipole method (MLFMM), memory and time efficient computations are possible. The efficiency of the proposed method is demonstrated in several numerical examples.